In recent years, the importance of telecommunication systems increases more and more. Since the number of users as well as the load of the telecommunication network due to new communication services such as multimedia and the like grow, improved transmission methods are developed to ensure a reliable and sufficiently high data transfer, and monitoring of the communication networks has to be performed to recognize the performance level.
One approach for an improved transmission method is the asynchronous transfer mode (ATM) which represents a packet switching protocol providing a rapid transmission of data in broadband networks.
The ATM network comprises several network elements, for example so-called ATM switches. Said network elements are connected, e.g., to other ATM switches, or other network elements such as multiplexers, terminal devices, user equipment or the like.
To establish a connection between two ATM network elements, for example, due to a request for connection between two users, an ATM switch has to perform a channel selection (CS) or routing by routing algorithms to select a channel used for data transfer. The connection can be established, for example, by a virtual path (VP) or a virtual channel (VC), which depends on the selected connection type. When a channel is selected, a connection admission control (CAC) is executed to check whether the currently selected channel can accommodate the required new connection.
If the CAC decides that the currently selected channel is sufficient to the requirements of the connection request, the selected connection is assumed as succeeded, and the connection between the two ATM network elements is established. Otherwise, if the CAC decides that the currently selected channel is not sufficient, the selected connection is assumed as failed, and a new channel is to be selected by the CS.
In the channel selection, there is a hierarchical order of objects. The smallest unit of said order is a so-called end point, for example an end point of a VC connection, if the selected connection type is a VC type, or an end point of a VP connection, if the selected connection type is a VP type. The next stage is a so-called end point group which comprises several end points with common characteristics. Finally, a so-called route is defined which comprises end point groups.
For the connection itself, different transmission modes can be requested. For example, it is possible to request a constant bit rate (cbr) transmission service or a variable bit rate (vbr) (e.g. a real time variable bit rate (rtvbr)) transmission service. Moreover, the required bit rate, i.e. the bandwidth, for the respective transmission service can be set. For the above mentioned CAC, it is therefore necessary to check whether or not the selected channel is able to perform the transmission with the set conditions (transmission service type, bandwidth).
As mentioned above, the network performance is to be monitored, for example, in order to decide whether the existing network structure is sufficient or how it is to be improved. For this purpose, it is necessary to gain statistical data of communication services such as channel selection or the like. This statistical data should inform, for example, about the requested bandwidth, the requested transmission mode, whether the request was successful or not, and the like, in combination with a correct identification of the respective end point or the like in the network to which the request is directed.
In this connection, a problem exists to measure and keep statistical data of a working channel selection algorithm. Moreover, it is difficult to adapt the respective statistical data obtaining method to different requirements and/or network abilities. Furthermore, a method which may provide a sufficient flexibility in obtaining the statistical data is complex, and hence a high processing power is needed to perform the respective measurements, which in turn increases costs.